Electric meter detection method and power conversion device

Abstract

This application provides a method for testing electricity meters and a power conversion device. The method includes: injecting a corresponding first input reactive power into each phase line; acquiring the first detected reactive power of each detection branch; adjusting the reactive power injected into each phase line to a corresponding second input reactive power based on the change in input reactive power for each phase line, wherein the changes in input reactive power for each phase line are not equal; acquiring the second detected reactive power of each detection branch; calculating the change in detected reactive power for each detection branch based on the first and second detected reactive power detected in each detection branch; and determining the wiring test result of the electricity meter based on the change in input reactive power for each phase line and the change in detected reactive power for each detection branch. The electricity meter testing method provided in this application can quickly and accurately determine the wiring test result of the electricity meter without considering PV and battery energy.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a method for testing electricity meters and a power conversion device. Background Technology

[0002] Photovoltaic (PV) or solar-energy storage (PV-ESD) systems typically have electricity meters installed at the grid connection point. These meters monitor energy transfer between the system and the grid, enabling power dispatch and metering functions. Currently, the mainstream method uses three-phase meters with external current transformers (CTs). However, three-phase meters with external CTs are prone to wiring problems, such as incorrect wiring, incorrect phase sequence, or reverse connection. This can lead to errors in power dispatch logic and inaccurate metering results, resulting in abnormal situations where the PV or ESD system fails to supply power to the load or discharges into the grid. Therefore, meter wiring testing is necessary.

[0003] The most commonly used meter wiring detection scheme in related technologies involves the photovoltaic system or photovoltaic-storage system actively performing multiple charge and discharge cycles based on active power commands. The difference between the actual active power detected by the meter and the active power command is used to determine whether the meter is wired incorrectly. However, this detection scheme has many limitations. For example, it is limited by the power generation status of the photovoltaic modules and / or the energy storage status of the battery pack, which can easily lead to excessively long detection times and unstable active power. Furthermore, changes in electrical load can easily cause fluctuations in active power, which may also lead to detection failure. Summary of the Invention

[0004] In view of this, this application provides a meter testing method and a power conversion device, which can test the meter by outputting reactive power from a multiphase inverter, and can quickly and accurately determine the meter's wiring test results without considering the output energy of photovoltaic modules and battery energy.

[0005] The first aspect of this application provides a meter detection method applied to a multiphase inverter. At least two phase lines of the AC terminal of the multiphase inverter are connected to the power grid via a meter. The meter includes at least two detection branches, which are used to detect the real-time reactive power transmitted on the corresponding phase lines. The method includes: injecting a corresponding first input reactive power into each phase line; acquiring the first detected reactive power detected by each detection branch; adjusting the first input reactive power injected into each phase line to a corresponding second input reactive power based on the change in input reactive power corresponding to each phase line; wherein the change in input reactive power corresponding to each phase line is not equal; acquiring the second detected reactive power detected by each detection branch; calculating the change in detected reactive power corresponding to each detection branch based on the first and second detected reactive power detected by each detection branch; and determining the meter's wiring detection result based on the change in input reactive power corresponding to each phase line and the change in detected reactive power corresponding to each detection branch.

[0006] In one embodiment, the wiring test result of the meter is determined based on the change in input reactive power corresponding to each phase line and the change in detected reactive power corresponding to each test branch. This includes: determining the change range corresponding to each phase line based on the change in input reactive power corresponding to each phase line, wherein each change range does not overlap; matching the change in detected reactive power corresponding to each test branch with each change range to determine the phase line actually tested for each test branch.

[0007] In one embodiment, the wiring test result of the meter is determined based on the change in input reactive power corresponding to each phase line and the change in detected reactive power corresponding to each detection branch. The method further includes determining that a wiring error exists when any change in detected reactive power does not match any of the change ranges.

[0008] In one embodiment, the multiphase inverter is configured with a preset correspondence between phase lines and detection branches; the wiring detection result of the meter is determined based on the input reactive power change corresponding to each phase line and the detected reactive power change corresponding to each detection branch, including: calculating the deviation between the absolute value of each detected reactive power change and the absolute value of the corresponding input reactive power change according to the preset correspondence; when the absolute value of all deviation values ​​is less than or equal to a preset error threshold, the preset correspondence is determined to be correct.

[0009] In one embodiment, the wiring test result of the meter is determined based on the change in input reactive power corresponding to each phase line and the change in detected reactive power corresponding to each detection branch. The method further includes determining that there is a wiring error or phase sequence error when the absolute value of any deviation value is greater than a preset error threshold.

[0010] In one embodiment, the wiring test result of the meter is determined based on the input reactive power change corresponding to each phase line and the detected reactive power change corresponding to each detection branch. This includes: sorting the absolute values ​​of each input reactive power change in the same sorting manner, and sorting the absolute values ​​of each detected reactive power change; calculating the deviation between the absolute values ​​of the input reactive power change and the absolute values ​​of the detected reactive power change in the same ranking; and determining that a wiring error exists when the absolute value of any deviation is greater than a preset error threshold.

[0011] In one embodiment, the wiring test result of the meter is determined based on the change in input reactive power corresponding to each phase line and the change in detected reactive power corresponding to each test branch, including: determining the reverse connection test result of the corresponding test branch based on the sign of the change in detected reactive power.

[0012] In one embodiment, determining the reverse connection detection result of the corresponding detection branch based on the sign of the detected reactive power change includes: when the sign of the detected reactive power change is inconsistent with the preset sign, and the absolute value of the detected reactive power change is greater than the preset measurement deviation threshold, it is determined that there is a reverse connection error in the detection branch corresponding to the detected reactive power change.

[0013] In one embodiment, before injecting the corresponding first input reactive power into each phase line, the method further includes: detecting power fluctuation data of the detected reactive power sampled by the meter within a preset time period; and when the power fluctuation data are all less than a preset fluctuation threshold, performing the step of injecting the corresponding first input reactive power into each phase line.

[0014] A second aspect of this application provides a power conversion device, including a multiphase inverter and a controller. At least two phase lines of the AC terminal of the multiphase inverter are connected to the power grid via an electricity meter. The electricity meter includes at least two detection branches, which are used to detect the real-time reactive power transmitted on the corresponding phase lines. The controller is used to execute the electricity meter detection method as described in any of the preceding claims.

[0015] The meter testing method provided in this application is applied to a multiphase inverter. It injects a corresponding first input reactive power into each phase line of the multiphase inverter. Then, based on the change in the input reactive power of each phase line, the first input reactive power injected into each phase line is adjusted to a second input reactive power. Simultaneously, it acquires the first and second detected reactive power of each phase line when the first and second input reactive power are injected into the multiphase inverter, respectively, to determine the change in detected reactive power of the corresponding phase line. Since, when each detection branch is correctly connected according to a preset correspondence, the deviation between the change in input reactive power of each phase line and the change in detected reactive power of the corresponding detection branch should be within a preset error range. Furthermore, since the change in input reactive power of each phase line is not equal, the meter's wiring test result can be determined based on the change in input reactive power of each phase line and the change in detected reactive power of each detection branch. For example, it can determine whether there are wiring errors, phase sequence errors, or reverse connection errors. Furthermore, since the meter testing method provided in this application tests the meter by outputting reactive power from a multiphase inverter, the meter testing method provided in this application does not need to consider complex factors such as photovoltaic modules and battery power involved in the active power. In other words, the meter testing method of this application makes the meter wiring results faster and more accurate. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation on the scope of protection of this application. In the various drawings, similar components are numbered similarly.

[0017] Figure 1 This is a schematic diagram illustrating the application environment of the meter testing method provided in one embodiment of this application.

[0018] Figure 2 This is a schematic diagram of the structure of an electricity meter in one embodiment of this application.

[0019] Figure 3 This is a schematic diagram of the structure of the meter in another embodiment of this application.

[0020] Figure 4 This is a schematic diagram of the application environment for a meter testing method provided in another embodiment of this application.

[0021] Figure 5 This is a schematic flowchart of an embodiment of the electricity meter testing method provided in this application.

[0022] Figure 6This is a preset control loop used in one embodiment of the present application to inject corresponding input reactive power into each phase line.

[0023] Figure 7 This diagram illustrates the reactive voltage and reactive current on each phase line of a multiphase inverter in a three-phase coordinate system.

[0024] Figure 8 This is a flowchart illustrating the sub-steps of step S506 provided in an embodiment of this application.

[0025] Figure 9 This is a partial flowchart of step S506 provided in another embodiment of this application.

[0026] Figure 10 This is a partial flowchart of step S506 provided in another embodiment of this application.

[0027] Figure 11 This is a flowchart illustrating the steps prior to step S501, as provided in an embodiment of this application.

[0028] Figure 12 This is a flowchart illustrating a meter testing method provided in another embodiment of this application.

[0029] Figure 13 This is a block diagram of a power conversion device provided in an embodiment of this application.

[0030] Figure 14 A block diagram of an energy storage device provided in one embodiment of this application.

[0031] Figure 15 A functional block diagram of a computer-readable storage medium provided in an embodiment of this application. Detailed Implementation

[0032] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0033] In the following text, the terms "comprising," "having," and their cognates, which may be used in various embodiments of this application, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more combinations thereof. Furthermore, the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0034] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have an intervening component. When a component is considered to be "placed" on another component, it can be directly placed on the other component or may also have an intervening component.

[0035] It should also be noted that the methods disclosed in the embodiments of this application or the methods shown in the flowcharts include one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged, and some steps can also be deleted.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0037] Please see Figure 1 , Figure 1 This diagram illustrates the connection of a photovoltaic system 10 according to one embodiment of this application. Figure 1 In this system, the photovoltaic system 10 includes photovoltaic modules 101, a Maximum Power Point Tracking (MPPT) circuit 102, and a multiphase inverter 103. The output of the photovoltaic modules 101 is electrically connected to the input of the MPPT circuit 102. The output of the MPPT circuit 102 is electrically connected to the DC terminal of the multiphase inverter 103 via positive and negative DC buses (i.e., positive DC bus DC_BUS+ and negative DC bus DC_BUS-). At least two phases of the AC terminal of the multiphase inverter 103 are electrically connected to the electrical load 20. At least two phases of the AC terminal of the multiphase inverter 103 are also electrically connected to the power grid 40 via a meter 30, enabling the multiphase inverter 103 to establish an electrical connection with the power grid 40 and thus operate in a grid-connected state.

[0038] In some embodiments, the photovoltaic module 101 may include a single photovoltaic panel, or a plurality of photovoltaic panels connected in series, in parallel, or in a series-parallel configuration, without limitation herein.

[0039] The MPPT circuit 102 can be set independently, or it can be set inside the photovoltaic panel, or it can be integrated with the multiphase inverter 103; no limitation is made here. This application does not limit the specific circuit structure of the MPPT circuit; for example, the MPPT circuit may include a boost circuit.

[0040] exist Figure 1In the photovoltaic system 10 shown, the multiphase inverter 103 can be used to realize the inverter function. This application does not limit the circuit structure of the multiphase inverter 103. For example, the multiphase inverter 103 can be a full-bridge inverter or a half-bridge inverter, etc. This application also does not limit the number of phases at the AC terminal of the multiphase inverter 103.

[0041] The electrical load 20 can be various electrical devices, such as refrigerators and air conditioners. This application does not limit the specific type of electrical load 20.

[0042] The power grid 40 can be, for example, a municipal power grid or other power distribution system. This application does not limit the type of AC power in the power grid 40; for example, the power grid 40 can be single-phase AC, split-phase AC, three-phase AC, or other multi-phase AC. In this embodiment, a three-phase AC power grid is used as an example.

[0043] The meter 30 includes at least two detection branches 301, and each detection branch 301 is equipped with a voltage sampling terminal and a current sampling terminal for detecting the electrical parameters of the corresponding phase line. These electrical parameters may include, for example, the real-time reactive power, real-time active power, real-time phase current, and real-time phase voltage transmitted on the corresponding phase line. For example, please refer to [further details omitted]. Figures 1 to 3 The electricity meter 30 can be Figure 2 The external electricity meter shown, or it could be Figure 3The built-in meter is shown. Taking meter 30 as an example, which includes three detection branches 301, it can be understood that in each detection branch 301 of the external meter, the first end of detection branch 301 (not shown in the figure) is connected to the power grid 40, the second end of detection branch 301 (not shown in the figure) can be connected to the corresponding phase line of multiphase inverter 103 through a protection switch, and the third end of detection branch 301 serves as a terminal on the sampling line and is connected to the corresponding phase line. In each detection branch 301 of the built-in meter, the first end of detection branch 301 is connected to the power grid 40, and the second end of detection branch 301 is connected to multiphase inverter 103, without considering the sampling terminal. Taking meter 30 as an example of an external meter, the third end of detection branch 301 may include the sampling terminal of a potential transformer (PT) and a sampling terminal of a current transformer (CT). It is understandable that the sampling terminals on the CT are electrically connected to the corresponding phase and neutral lines. This allows the current in each phase line to be reduced to a value measurable by the meter 30 according to a set ratio, based on the principle of electromagnetic induction, enabling the meter 30 to detect the real-time current on the corresponding phase line. It is also understood that current has directionality; correspondingly, the CT has a current inlet terminal for incoming current and a current outlet terminal for outgoing current. The detection principle of the PT is similar to that of the CT, so it will not be elaborated further. It is also understood that if the first terminal of the detection branch 301 is not connected according to the preset correspondence, it will not affect the phase sequence of the meter; however, if the second and / or third terminals of the detection branch 301 are not connected according to the preset correspondence, it will affect the phase sequence of the meter, thereby affecting the accuracy of the electrical parameters.

[0044] Taking a multiphase inverter 103 as an example of a three-phase inverter, the A-phase line A1, B-phase line B1, and C-phase line C1 of the AC terminal of the multiphase inverter 103 are respectively connected to the first phase line A2, the second phase line B2, and the third phase line C2 of the power grid 40 through the meter 30. Correspondingly, the meter 30 includes a first detection branch DT1, a second detection branch DT2, and a third detection branch DT3, which are respectively connected to the corresponding phase lines of the AC terminal of the multiphase inverter 103 to detect the electrical parameters on the corresponding phase lines. It can be understood that, although not shown in the figure, the neutral line of the AC terminal of the multiphase inverter 103 is also connected to the neutral terminal of the power grid 40 through the meter 30.

[0045] Figure 1The photovoltaic system 10 shown can operate in a self-consumption mode. Specifically, the photovoltaic module 101 converts solar energy into direct current (DC) and outputs it to the MPPT circuit 102. The MPPT circuit 102 then transmits the DC power to the multiphase inverter 103 via positive and negative DC buses. The MPPT circuit 102 can be used to achieve maximum power point tracking (MPPT) of the output power of the photovoltaic module 101, ensuring that the multiphase inverter 103 is connected to the maximum output power of the photovoltaic module 101, thereby improving photovoltaic utilization. The multiphase inverter 103 also converts the DC power into alternating current (AC) and outputs it to the electrical load 20, enabling the electrical load 20 to operate. When the photovoltaic power output of the photovoltaic module 101 is insufficient to meet the demand of the electrical load 20, the power grid 40 can also work with the power supply system 10 to supply power to the electrical load 20. Correspondingly, when the photovoltaic power output by the photovoltaic module 101 has a surplus in addition to meeting the needs of the electrical load 20, the multiphase inverter 103 can also feed some of the AC power into the grid 40 to improve the economic efficiency of the power supply system 10. That is, the photovoltaic system 10 can also operate in the surplus power grid connection mode.

[0046] Please continue reading. Figure 4 In some embodiments, the photovoltaic system 10 also includes a battery pack 104. In this case, the photovoltaic system 10 may also be referred to as a photovoltaic energy storage system, or simply a photovoltaic-energy storage system.

[0047] The battery pack 104 includes one or more cells connected in series and / or parallel for storing or releasing energy. The positive terminal (+) of the battery pack 104 is electrically connected to the positive DC bus DC_BUS+, and the negative terminal (-) of the battery pack 104 is electrically connected to the negative DC bus DC_BUS-. Figure 2 In the photovoltaic system 10 shown, the multiphase inverter 103 can not only perform the inversion function but also the rectification function. Therefore, Figure 2 The multiphase inverter 103 in the system can also be called a bidirectional power conversion system (PCS). Thus, when the photovoltaic power output of the photovoltaic module 101 exceeds the power required to power the load 20, the battery pack 104 can draw energy from the positive and negative DC buses and store it. Furthermore, when the photovoltaic power output of the photovoltaic module 101 is insufficient to maintain the operation of the load 20, the battery pack 104 can discharge to the positive and negative DC buses to power the load 20 together with the photovoltaic module 101. In this way, the photovoltaic system 10 can achieve self-consumption. Figure 2In this system, when the photovoltaic power output of the photovoltaic module 101 and the discharge power of the battery pack 104 are insufficient to meet the demand of the electrical load 20, the grid 40 can also supply power to the electrical load 20 together with the power supply system 10. Correspondingly, when the photovoltaic power output of the photovoltaic module 101 exceeds the demand of the electrical load 20 and the battery pack 104, the multiphase inverter 103 can also feed some AC power into the grid 40 to improve the economic efficiency of the power supply system 10; that is, the photovoltaic system 10 can also operate in a surplus power grid connection mode. When the battery pack 104 is underpowered, the multiphase inverter 103 can also convert the AC power from the grid 40 into DC power to charge the battery pack 104.

[0048] Of course, in Figure 1 and Figure 4 In the photovoltaic system 10 shown, the photovoltaic power output by the photovoltaic modules 101 can also be entirely fed into the grid 40 through the multiphase inverter 103, meaning the photovoltaic system 10 can also operate in full grid-connected mode. Furthermore, in situations where grid 40 does not allow power feeding, Figure 1 and Figure 2 The photovoltaic system 10 can also operate in anti-reverse mode, that is, the photovoltaic system 10 is prohibited from feeding surplus electricity into the grid or feeding all of its electricity into the grid.

[0049] In some cases (such as when the power grid 40 fails or the power supply is unstable), the multiphase inverter 103 can also be disconnected from the power grid 40, so that the multiphase inverter 103 is in an off-grid operation state to prevent damage to the electrical load 20 and the multiphase inverter 103.

[0050] Understandable. Figure 1 The photovoltaic system 10 shown is or Figure 2 The illustrated photovoltaic-storage system uses a meter 30 installed at the grid connection point to detect energy transfer between the photovoltaic system 10 and the grid 40, thereby enabling power dispatch and metering functions for either the photovoltaic system 10 or the photovoltaic-storage system. Currently, the mainstream meter used is a three-phase meter with an external current transformer (CT). However, wiring of three-phase meters with external CTs is prone to problems, such as incorrect wiring, incorrect phase sequence, or reverse connection errors. This can lead to errors in power dispatch logic and inaccurate metering results, resulting in abnormal situations where the photovoltaic system 10 or the photovoltaic-storage system fails to supply power to the load 20 or discharges into the grid 40.

[0051] For example, when the external PT and external CT on any detection branch of meter 30 are not connected to the same phase line, such as when Figure 1When the external current transformer (CT) of the second detection branch DT2 of the meter 30 is connected to the A-phase line A1 of the multiphase inverter 103, and the external current transformer (PT) on the second detection branch DT2 is connected to the B-phase line B1, a wiring error occurs. When the direction of current flow to the power grid 40 is taken as positive, and the current input and output terminals of the external CT on the detection branch of the meter 30 are reversed, a reverse connection error occurs. When the first detection branch DT1, the second detection branch DT2, and the third detection branch DT3 of the meter 30 are not connected to the A-phase line A1, B-phase line B1, and C-phase line C1 of the multiphase inverter 103 according to the preset correspondence, for example, when the first detection branch DT1 is connected to the B-phase line B1, the second detection branch DT2 is connected to the A-phase line A1, and the third detection branch DT3 is connected to the C-phase line C1, the power detected by the first detection branch DT1 of the meter 30 does not match the actual real-time power of the A-phase line A1, and the power detected by the second detection branch DT2 does not match the actual real-time power of the B-phase line B1. At this time, a phase sequence error occurs.

[0052] The commonly used meter wiring detection scheme in related technologies involves the photovoltaic system 10 or the photovoltaic-storage system actively performing multiple charge-discharge cycles based on the active power command. The difference between the actual active power detected by the meter 30 and the active power command is used to determine whether the meter is wired incorrectly. However, this detection scheme has many limitations. For example, it is limited by the power generation state of the photovoltaic module 101 and / or the energy storage state of the battery pack 104 in the system, which can easily lead to excessively long detection times and unstable active power. In addition, changes in the electrical load 20 can easily cause fluctuations in active power, which may also lead to detection failure.

[0053] Based on this, this application provides a meter testing method applied to a multiphase inverter 103, which can reduce the power loss caused by meter testing and quickly and accurately determine the meter wiring test results.

[0054] It is worth noting that the meter testing method provided in this application, in addition to being applied to Figure 1 and Figure 2 The multiphase inverter 103 shown in the application scenario can also be applied to other multiphase inverters 103 connected to the power grid 40 via the meter 30. Figure 1 and Figure 2 The illustrated application environment diagram does not limit the meter testing method and power conversion equipment provided in this application.

[0055] Please see Figure 5 , Figure 5 This is a schematic flowchart illustrating an embodiment of a meter detection method provided in this application. Understandably, this meter detection method is applied to a multiphase inverter 103 and can be controlled by the controller of the multiphase inverter 103 (…). Figure 1 and Figure 2 (Not shown) is executed. The controller can be integrated into the multiphase inverter 103 or set up separately from the multiphase inverter 103. This meter detection method includes the following steps S501-S506.

[0056] Step S501: Inject the corresponding first input reactive power into each phase line respectively.

[0057] It is understandable that the power transmitted between the multiphase inverter 103 and the grid 40 includes both active and reactive power. The active power transmitted between the multiphase inverter 103 and the grid 40 can be used to power the electrical load 20, the electrical equipment on the grid 40, and the equivalent resistance of the lines, and is thus consumed. The reactive power transmitted between the multiphase inverter 103 and the grid 40 can be used to power the inductive electronic components in the photovoltaic system 10, the electrical load 20, and the electrical equipment on the grid 40, such as transformers and inductors, to establish a magnetic field, and to power the capacitive electronic components in the photovoltaic system 10, the electrical load 20, and the electrical equipment on the grid 40, such as capacitors, to establish an electric field, for energy exchange. During the energy exchange process, no active power is consumed to perform work. Therefore, without changing the structure of the photovoltaic system 10, without adding, reducing or replacing the electrical load 20, and without changing the electrical equipment in the power grid 40, the overall inductive reactance and capacitive reactance remain basically unchanged. In this way, the reactive power transmitted between the multiphase inverter 103 and the power grid 40 can remain basically stable, and the reactive power will not cause the consumption of active power.

[0058] In step S501, the controller can control the input reactive power of each phase line to the power grid 40 according to the first given reactive power corresponding to each phase line, so as to inject the corresponding first input reactive power into each phase line respectively. It can be understood that, ideally, the first input reactive power corresponding to each phase line is equal to the corresponding first given reactive power.

[0059] In step S501, the controller can generate modulation parameters corresponding to each phase line based on a preset control loop and the first input reactive power corresponding to each phase line. This allows the controller to generate control signals for the corresponding phase line based on each modulation parameter, thereby controlling the inverter circuit in the multiphase inverter 103 and injecting the corresponding first input reactive power into each phase line. The preset control loop may include at least one of a voltage loop, current loop, power loop, combined loop, or other control loops. This application does not limit the specific loop. The preset control loop may include one or more control loops / controllers, such as adders, subtractors, derivative controllers (D), proportional-integral (PI) controllers, proportional-integral-derivative (PI-DI) controllers, limiters, etc. This application does not limit these.

[0060] For example, please see Figure 6 , Figure 6 This embodiment of the application provides a preset control loop for injecting corresponding input reactive power into each phase line. Specifically, the controller can acquire the actual phase voltage U of each phase line at the AC terminal of the multiphase inverter 103 via a voltage sampling circuit. abc That is, the actual phase voltage U of phase A a The actual phase voltage U of phase B b and the actual phase voltage U of phase C c The controller also collects the actual phase current I of each phase line at the AC terminal of the multiphase inverter 103 through a current sampling circuit. abc That is, the actual phase current I of phase A. a The actual phase current I of phase B b and the actual phase current I of phase C c .in this way, Figure 6 The preset control loop shown can be based on the actual phase voltage U of each phase line. abc The actual phase current I of each phase line abc Given active power P set and given reactive power Q set Calculations are performed to obtain the control signal for each phase line, and each phase arm of the three-phase inverter 103 is controlled separately, thereby injecting the corresponding first input reactive power into each phase line. Wherein, the given active power P... set This includes the given active power for each phase, and the given active power for each phase can be 0. The given reactive power Q... setThis includes the given reactive power for each phase line, and the given reactive power for each phase line may be equal or unequal. This application does not limit the specific value of the first input reactive power for each phase line. The control signal may be, for example, a pulse width modulation (PWM) signal. (Further details are omitted here.) Figure 6 The specific calculation process of the preset control loop shown is not described in detail here, and those skilled in the art can adjust it according to the actual situation. Figure 6 The preset control loop shown can be adjusted accordingly, or other preset control loops can be used to inject the corresponding first input reactive power into each phase line. This application does not limit the specific algorithm for implementing step S501.

[0061] Step S502: Obtain the first detected reactive power of each detection branch.

[0062] It is understood that the multiphase inverter 103 is configured with a preset correspondence between each phase line and each detection branch. After the multiphase inverter 103 injects the corresponding first input reactive power into each phase line, each detection branch of the meter 30 can detect the actual reactive power on the corresponding phase line as the first detected reactive power and display it. It is worth noting that, due to possible wiring problems in each detection branch on the meter 30, the first detected reactive power detected in step S502 may not be accurate.

[0063] In some embodiments, the controller of the multiphase inverter 103 may be communicatively connected to the meter 30 to obtain the first detected reactive power detected by each detection branch 301 of the meter 30. The communication connection may be a wired communication connection or a wireless communication connection, and this application is not limited to this.

[0064] Step S503: Based on the change in input reactive power corresponding to each phase line, adjust the first input reactive power injected into each phase line to the corresponding second input reactive power; wherein, the change in input reactive power corresponding to each phase line is not equal.

[0065] The change in input reactive power can be a preset value, and it can also be used as the given reactive power change for the corresponding phase line. In other words, in step S503, the first given reactive power for each phase line can be adjusted to a second given reactive power based on the change in input reactive power for each phase line. Furthermore, the controller can control the input reactive power of each phase line to the grid 40 according to the second given reactive power for each phase line, thereby injecting the corresponding second input reactive power into each phase line, making the actual change in input reactive power for each phase line close to or even equal to the preset change in input reactive power.

[0066] The minimum value of the input reactive power change can be adjusted to correspond to the detection accuracy of different meters. This application does not impose any specific numerical limit on the input reactive power change for each phase line.

[0067] Step S504: Obtain the second detected reactive power detected by each detection branch.

[0068] It is understood that after injecting the corresponding second input reactive power into each phase line in step S503, in step S504, each detection branch of the multiphase inverter 103 can detect the actual reactive power on the corresponding phase line as the second detected reactive power and display it.

[0069] Step S505: Calculate the change in reactive power for each detection branch based on the first and second detected reactive power detected by each detection branch.

[0070] In this embodiment, the difference between the first actual reactive power and the second actual reactive power can be used as the change in detected reactive power of the corresponding detection branch. In other embodiments, the power difference between the second actual reactive power and the first actual reactive power can also be used as the change in detected reactive power of the corresponding detection branch. This application does not limit this to any particular embodiment.

[0071] Step S506: Determine the wiring test result of the meter based on the change in input reactive power corresponding to each phase line and the change in detected reactive power corresponding to each detection branch.

[0072] It is understandable that when each detection branch of meter 30 is connected to the corresponding phase line according to a preset correspondence, for example, the first detection branch DT1 is connected to phase line A1, the second detection branch DT2 is connected to phase line B1, and the third detection branch DT3 is connected to phase line C1, then under normal circumstances, the deviation between the input reactive power change of each phase line and the detected reactive power change of the corresponding detection branch should be within the preset error range. Furthermore, since the reactive power change is related to reactive voltage and reactive current, when the deviation between the input reactive power change of each phase line and the detected reactive power change of the corresponding detection branch is not within the preset error range, the connection status of the external CT and external PT on the detection branch can be inferred based on the detected reactive power change and the input reactive power change, thereby determining the wiring detection result.

[0073] Specifically, please refer to Figure 7 , Figure 7 This diagram illustrates the reactive voltage and reactive current on each phase line of the multiphase inverter 103 in a three-phase coordinate system. To simplify the explanation, Figure 7Assuming an ideal situation, the reactive voltage and reactive current on each phase line form a 90° angle, the first input reactive power on each phase line is 0, and the current meter 30 detects the second input reactive power on each phase line. In other words, the second input reactive power detected by the current meter 30 on each phase line can be used as the measure of reactive power change. Thus, the following four scenarios are possible:

[0074] (1) When each detection branch of the meter 30 is correctly connected to the corresponding phase line according to the preset correspondence, such as the first detection branch DT1 connected to phase A line A1, the second detection branch DT2 connected to phase B line B1, and the third detection branch DT3 connected to phase C line C1, the following reactive power change of each phase line can be obtained through the meter 30:

[0075] Q a1 =U qa ×I qa

[0076] Q b1 =U qb ×I qb

[0077] Q c1 =U qc ×I qc

[0078] Among them, Q a1 This indicates the change in reactive power obtained through the first detection branch DT1, and it is equal to the change in input reactive power on phase A line A1; U qa I represents the reactive voltage on phase A line A1; qa Q represents the reactive current on phase A1. b1 This indicates the change in reactive power obtained through the second detection branch DT2, and it is equal to the change in input reactive power on phase B line B1; U qb This represents the reactive voltage on phase B1; I qb This represents the reactive current on phase B1. Q c1 This indicates the change in reactive power obtained through the third detection branch DT3, and it is equal to the change in input reactive power on phase C line C1; U qc I represents the reactive voltage on phase C1; qc This represents the reactive current on phase C1.

[0079] (2) When the external PT of the second detection branch DT2 is connected to the B-phase line B1 of the AC inverter 103, and the external CT of the second detection branch DT2 is connected to the A-phase line A1 of the AC inverter 103, that is, when the second detection branch DT2 of the meter 30 has a wiring error, the following reactive power change of each phase line is obtained through the meter 30:

[0080] Q a2 =U qa ×I qa

[0081] Q b2 =-U qb ×I qb ×sin30°

[0082] Q c2 =U qc ×I qc

[0083] At this time, the change in reactive power Q obtained through the second detection branch DT2 b2 The change in input reactive power Q on phase B line B1 b1 They are not equal.

[0084] (3) When the external PT of the second detection branch DT2 is connected to the B phase line B1 of the AC inverter 103, and the external CT on the second detection branch DT2 is reversed, that is, when the second detection branch DT2 of the meter 30 is reversed, the following reactive power change of each phase line is obtained through the meter 30:

[0085] Q a3 =U qa ×I qa

[0086] Q b3 =-U qb ×I qb

[0087] Q c3 =U qc ×I qc

[0088] At this time, the change in reactive power Q obtained through the second detection branch DT2 b3 The change in input reactive power Q on phase B line B1 b1 They are opposites.

[0089] (4) When the external PT and external CT of the first detection branch DT1 are both connected to phase B line B1, the external PT and external CT of the second detection branch DT2 are both connected to phase A line A1, and the external PT and external CT of the third detection branch DT3 are both connected to phase C line C1, that is, when the phase sequence error occurs in the second detection branch DT2 of the meter 30, the reactive power of each phase line is obtained through the meter 30 as follows:

[0090] Q a3 =U qb ×I qb

[0091] Q b3 =U qa ×I qa

[0092] Q c3 =U qc ×I qc

[0093] At this time, the change in reactive power Q obtained through the second detection branch DT2 b3 In fact, it is equal to the change in reactive power Q on phase A1. a1 The change in reactive power Q obtained through the first detection branch DT1 a3 In fact, it is equal to the change in input reactive power Q on phase B line B1. b1 .

[0094] Obviously, based on the above analysis, when different amounts of reactive power change are injected into the three phase lines of the three-phase inverter 103, the wiring method of the corresponding detection branch can be determined according to the reactive power change fed back by the meter 30, thereby detecting wiring errors, phase sequence errors, or reverse connection errors of the meter 30.

[0095] Specifically, when each detection branch of meter 30 is connected to its corresponding phase line according to a preset correspondence, under normal circumstances, the deviation between the input reactive power change of each phase line and the detected reactive power change of the corresponding detection branch should be within a preset error range. Even if a reverse connection error exists, the absolute value of the input reactive power change of each phase line and the absolute value of the detected reactive power change of the corresponding detection branch will still fall within the preset error range. Conversely, if the deviation between the absolute value of the input reactive power change and the absolute value of the detected reactive power change of the corresponding detection branch deviates from the preset error range, it indicates that the corresponding detection branch is very likely to have other wiring problems.

[0096] Since the changes in input reactive power corresponding to each phase are not equal, even if the detection branch is affected by detection errors, the changes in reactive power detected by each phase should be approximately within the same range as the changes in input reactive power of the corresponding phase. Therefore, each change in reactive power detected can be compared with all changes in input reactive power to determine the actual change in input reactive power corresponding to each change in reactive power detected, thereby correcting phase sequence errors. Alternatively, if there is a large deviation between the changes in reactive power detected and all changes in input reactive power, it indicates that there may be a wiring error in the corresponding detection branch. Thus, in step S506, the wiring detection result of the meter can be determined based on the changes in input reactive power corresponding to each phase and the changes in reactive power detected for each phase.

[0097] In summary, the meter detection method provided in this application injects a corresponding first input reactive power into each phase line of the multiphase inverter 103, and then adjusts the first input reactive power injected into each phase line to a second input reactive power according to the change in the input reactive power corresponding to each phase line. At the same time, it also acquires the first detected reactive power and the second detected reactive power of each phase line detected by the meter 30 when the first input reactive power and the second input reactive power are injected into the multiphase inverter 103, so as to determine the change in the detected reactive power of the corresponding phase line according to the first detected reactive power and the second detected reactive power of each phase line. In this method, since each detection branch is correctly connected according to the preset correspondence, the deviation between the input reactive power change of each phase line and the detected reactive power change of the corresponding detection branch should be within the preset error range. Furthermore, since the input reactive power change of each phase line is not equal, the meter wiring test result can be determined based on the input reactive power change of each phase line and the detected reactive power change of each detection branch. For example, it can determine whether there are wiring errors, phase sequence errors, or reverse connection errors. Moreover, since the meter testing method provided in this application detects the meter 30 by outputting reactive power from the multiphase inverter 103, it does not need to consider complex factors such as the photovoltaic modules and battery power involved in the active power. Therefore, the meter testing method of this application makes the meter wiring results faster and more accurate.

[0098] Please see Figure 8 In some embodiments, step S506 includes the following sub-steps:

[0099] Step S801: Determine the range of changes in reactive power for each phase line based on the change in input reactive power for each phase line, wherein each range of changes does not overlap.

[0100] The change range represents a range of values ​​and can be used to measure the magnitude of the change in reactive power. In some embodiments, the sum of each input reactive power change and a preset tolerance value can be calculated sequentially as the upper limit of the change range for the corresponding phase line, and the difference between each input reactive power change and the preset tolerance value can be calculated sequentially as the lower limit of the change range for the corresponding phase line.

[0101] The preset tolerance value can be adjusted according to the detection accuracy of the meter 30. This application does not limit the specific value of the preset tolerance value.

[0102] Step S802: Match the change in reactive power corresponding to each detection branch with each change interval to determine the actual phase line to be detected for each detection branch.

[0103] In step S802, when the detected reactive power change falls within a change range, it can be determined that the detected reactive power change matches the change range, thereby determining the detection branch corresponding to the detected reactive power change and connecting it to the phase line corresponding to the change range.

[0104] If the actual phase line corresponding to each detection branch determined in step S802 does not match the preset correspondence, the preset correspondence can be updated according to the detection result of step S802, or a phase sequence error reminder can be output to remind the user to reconnect the meter 30.

[0105] Thus, by executing steps S801 to S802, when a phase sequence error occurs in the meter 30, the preset correspondence can be updated in a timely manner or the user can be reminded to reconnect. This reduces the probability that the photovoltaic system 10 uses incorrect electrical parameters for calculation, improves the safety of the photovoltaic system 10, and effectively reduces the time spent troubleshooting meter errors, thereby improving work efficiency. In some embodiments, power calculation can also be performed based on the updated preset correspondence, which reduces the number of steps required for user reconnection and simplifies user operation.

[0106] In some embodiments, step S506 further includes:

[0107] If any detected change in reactive power does not match any of the change ranges, a wiring error is determined.

[0108] It is understandable that if any detected reactive power change does not match any of the change ranges, it indicates that the external PT and / or external CT of the detection branch corresponding to the detected reactive power change may be misconnected, causing the detected reactive power change to not match any of the change ranges. Thus, it can be determined that there is a wiring error in the detection branch of meter 30 corresponding to the detected reactive power change.

[0109] Please see Figure 9 In some embodiments, the multiphase inverter is configured with a preset correspondence between phase lines and detection branches, and step S506 further includes:

[0110] Step S901: Calculate the deviation between the absolute value of each detected reactive power change and the absolute value of the corresponding input reactive power change, based on the preset correspondence.

[0111] In some embodiments, the absolute value of the detected reactive power change can be obtained as a first value, the absolute value of the corresponding input reactive power change can be obtained as a second value, and the difference between the first value and the second value can be calculated as a deviation value.

[0112] Step S902: When the absolute value of all deviation values ​​is less than or equal to the preset error threshold, the preset correspondence is confirmed to be correct.

[0113] The preset error threshold represents the maximum absolute value of the deviation. Therefore, when the absolute value of the deviation is less than or equal to the preset error threshold, it indicates that the current deviation is within an acceptable range. This ensures that the detected change in reactive power corresponds to the input change in reactive power according to a preset relationship.

[0114] In summary, by executing steps S901 to S902, it can be determined whether each detection branch of the meter 30 conforms to the preset correspondence with each phase line of the multiphase inverter 103, thereby enabling rapid troubleshooting of the wiring of the meter 30.

[0115] In some embodiments, step S506 further includes:

[0116] When the absolute value of any deviation is greater than the preset error threshold, it is determined that there is a wiring error or a phase sequence error.

[0117] It is understandable that when the absolute value of the deviation exceeds the preset error threshold, it indicates that the current deviation value is outside the range under the scenario of correct meter wiring. Therefore, the detection branch corresponding to the detected reactive power change may have wiring or phase sequence errors, causing the connection relationship between the detection branch and the corresponding phase line to not conform to the preset correspondence. Thus, by executing this embodiment, the detection branch on the meter 30 that may have connection errors can be quickly identified, improving the efficiency of troubleshooting the meter 30.

[0118] Please see Figure 10 In some embodiments, step S506 further includes the following sub-steps:

[0119] Step S101: Sort the absolute values ​​of each input reactive power change and the absolute values ​​of each detected reactive power change in the same sorting method.

[0120] The sorting method can be, for example, sorting from largest to smallest, or sorting from smallest to largest. For instance, in one embodiment, step S101 can involve sorting the absolute values ​​of each input reactive power change from largest to smallest, and sorting the absolute values ​​of each detected reactive power change from largest to smallest.

[0121] Step S102: Calculate the deviation between the absolute value of the input reactive power change and the absolute value of the detected reactive power change for the same position.

[0122] In one embodiment, the deviation value can be calculated as the difference between the absolute value of the input reactive power change and the absolute value of the detected reactive power change for the same ranking. In other embodiments, the deviation value can also be calculated as the difference between the absolute value of the detected reactive power change and the absolute value of the input reactive power change for the same ranking. This application does not impose any limitations on this.

[0123] Step S103: When the absolute value of any deviation is greater than the preset error threshold, a wiring error is determined to exist.

[0124] It is understandable that when the meter 30 is correctly connected, or if there is a reverse connection error or a phase sequence error, each detected reactive power change and the actual corresponding input reactive power change will still be roughly in the same range. Therefore, after executing steps S101 to S102, even if the meter 30 has a reverse connection error or a phase sequence error, each detected reactive power change and the actual corresponding input reactive power change can still be in the same position.

[0125] When the absolute value of any deviation is greater than the preset error threshold, it indicates that the detected reactive power change does not match any input reactive power change. In this case, the external PT or external CT on the detection branch corresponding to the detected reactive power change may be connected to other phase lines, resulting in a wiring error.

[0126] In summary, by executing steps S101 to S103, it can be determined whether there is a wiring error in the meter 30, so that the user can be promptly reminded when a wiring error occurs.

[0127] In some embodiments, step S506 further includes:

[0128] The reverse connection test result of the corresponding test branch is determined based on the sign of the change in reactive power.

[0129] For example, if the sign of the detected reactive power change is opposite to the sign of the corresponding input reactive power change, it indicates a reverse connection error in the corresponding detection branch. If the sign of the detected reactive power change is the same as the sign of the corresponding input reactive power change, it indicates that there is no reverse connection error in the corresponding detection branch.

[0130] To improve detection accuracy, in some embodiments, the reverse connection detection result of the corresponding detection branch is determined based on the sign of the detected reactive power change, and the method further includes:

[0131] When the sign of the detected reactive power change is inconsistent with the preset sign, and the absolute value of the detected reactive power change is greater than the preset measurement deviation threshold, it is determined that there is a reverse connection error in the detection branch corresponding to the detected reactive power change.

[0132] The preset measurement deviation threshold is used to represent the absolute value of the difference between the input reactive power change and the meter accuracy error threshold. The preset sign is the sign of the input reactive power change corresponding to the detected reactive power change.

[0133] Thus, when the sign of the detected reactive power change is inconsistent with the preset sign, and the absolute value of the detected reactive power change is greater than the preset measurement deviation threshold, it indicates that the sign of the detected reactive power change is opposite to that of the input reactive power change, and the deviation between the absolute value of the detected reactive power change and the absolute value of the input reactive power change is less than the meter accuracy error threshold. In this case, it can be considered that there is a reverse connection error in the detection branch corresponding to the detected reactive power change.

[0134] Please see Figure 11 In some embodiments, before performing step S501, the meter detection method further includes the following steps S111-S112.

[0135] Step S111: Detect the power fluctuation data of reactive power sampled by the meter within a preset time period.

[0136] The preset duration may include several data acquisition cycles. The multiphase inverter 103 can periodically acquire the detected reactive power of each phase line sampled by the meter 30 according to the preset data acquisition cycles. Power fluctuation data is used to measure the stability of the detected reactive power on the corresponding phase line within the preset duration. Power fluctuation data may be, for example, at least one of the following: the deviation between the detected reactive power and the initial reactive power, the difference between the detected reactive power and the minimum reactive power, and the difference between the detected reactive power and the maximum reactive power. In other embodiments, the power fluctuation data may also include average value, variance, etc. This application does not limit the specific type of power fluctuation data.

[0137] For example, in some embodiments, the power fluctuation data can be the difference between the detected reactive power and the initial reactive power. Thus, in step S111, the first detected reactive power sampled for each phase line within a preset time period can be recorded as the initial reactive power of the corresponding phase line. Then, in each subsequent data acquisition cycle, the difference between the acquired detected reactive power and the initial reactive power is recorded as the power fluctuation data.

[0138] In other embodiments, the real-time reactive power detected by the meter at the initial moment can be used as the initial reactive power, maximum reactive power, and minimum reactive power. In each data acquisition cycle, a first difference between the real-time reactive power and the initial reactive power, a second difference between the real-time reactive power and the maximum reactive power, and a third difference between the real-time reactive power and the minimum reactive power are calculated. These first, second, and third differences are then used as power fluctuation data.

[0139] Step S112: When the power fluctuation data are all less than the preset fluctuation threshold, perform the step of injecting the corresponding first input reactive power into each phase line respectively.

[0140] Accordingly, in some embodiments, a preset fluctuation threshold is used to represent a critical value for acceptable power deviation. When the power fluctuation data is less than the preset fluctuation threshold, it indicates that the deviation between the detected reactive power and the initial reactive power is within an acceptable range, and the fluctuation is small; when the power fluctuation data is greater than the preset fluctuation threshold, it indicates that the deviation between the detected reactive power and the initial reactive power exceeds an acceptable range, and the fluctuation is large.

[0141] It is understandable that when the power fluctuation data are all less than the preset fluctuation threshold, it indicates that the fluctuation of the detected reactive power of each phase line on the current multiphase inverter 103 is small and the stability is good. At this time, continuing to execute the step of injecting the corresponding first input reactive power into each phase line can reduce the impact of the power fluctuation on each phase line on the injected first input reactive power.

[0142] In other embodiments, step S111 can be executed before executing steps S502, S503 and S504, so that steps S502, S503 and S504 are executed only when the power fluctuation data are all less than the preset fluctuation threshold, thereby reducing the impact of power fluctuation on the execution of the corresponding steps and improving the accuracy of the meter detection method.

[0143] Please refer to the following: Figure 1 and Figure 12 , Figure 12 This is a flowchart illustrating a meter testing method provided in another embodiment of this application, and Figure 12 The meter testing method shown can also be executed by the controller of the multiphase inverter 103. Figure 12 The illustrated meter testing method includes the following steps S121-S147. Depending on different requirements, the order of the steps in this flowchart can be changed, and some steps can be omitted.

[0144] Step S121: The multiphase inverter is powered on and enters the meter detection cycle.

[0145] The meter detection cycle can be, for example, a meter detection state machine configured in the multiphase inverter 103. Thus, in response to a power-on event, the multiphase inverter 103 can enter the meter detection state and perform the following steps to detect the meter 30.

[0146] In some embodiments, after the multiphase inverter 103 is powered on, it can communicate with the electricity meter 30 to determine whether the electricity meter 30 is connected to the multiphase inverter 103. And when the multiphase inverter 103 determines that it is connected to the electricity meter 30, the multiphase inverter 103 enters the electricity meter detection state.

[0147] Step S122: Receive the control command from the host computer and confirm whether to actively perform meter detection.

[0148] In some embodiments, the host computer (not shown in the figure) may be, for example, a user's terminal device (such as a mobile phone, tablet, remote control, computer, etc.) or an industrial control computer. The controller of the multiphase inverter 103 can receive control commands sent by the host computer via wireless or wired communication.

[0149] Control commands may include, for example, meter detection commands sent by a host computer. In some embodiments, the host computer may send a meter detection command to the multiphase inverter 103 after confirming that the photovoltaic system 10 is connected to the grid following power-on.

[0150] It is understood that in some embodiments, when the connection method of the meter 30 has not changed in a short period of time and the previous meter detection result indicates that the meter can continue to be used (e.g., when a phase sequence error and / or reverse connection error occurs), the previous meter detection result can be directly used after the multiphase inverter 103 is powered on. In some embodiments, the memory of the multiphase inverter 103 is provided with an active meter detection flag bit. When the active meter detection flag bit is set, it indicates that the multiphase inverter 103 directly performs meter detection. When the active meter detection flag bit is reset, it indicates that the multiphase inverter 103 has already performed meter detection in a short period of time, and the previous meter detection result can be referenced.

[0151] The active meter detection flag can be set or reset based on instructions sent by the host computer. For example, after the photovoltaic system 10 is powered on, the host computer confirms whether the meter 30 has been reconnected by interacting with the user or communicating with the meter 30. Thus, when the host computer confirms that the meter 30 has been reconnected, it sends an instruction to the multiphase inverter 103 to set the active meter detection flag; conversely, when the host computer confirms that the meter 30 has not been reconnected and a meter test has been performed within a short period (e.g., within 48 hours), it sends an instruction to the multiphase inverter 103 to reset the active meter detection flag.

[0152] Step S123: If it is confirmed that the meter will not be tested actively, check whether there is a wiring error in the previous meter test result.

[0153] If the previous meter reading indicates no wiring error, proceed to step S124. If the previous meter reading confirms a wiring error, proceed to step S125.

[0154] Step S124: Reset the alarm flag of the meter, set the meter detection completion flag, and end the current meter detection cycle.

[0155] Step S125: Confirm whether the meter detection completion flag is in the reset state.

[0156] When the meter detection completion flag is in the reset state, it indicates that the meter detection is not completed, and the process jumps to step S126; when the meter detection completion flag is in the set state, it indicates that the meter 30 has completed the meter detection and the current detection cycle ends.

[0157] Step S126: Confirm whether the meter start detection flag is in the set state.

[0158] When the meter start detection flag is confirmed to be in the set state, the process jumps to step S127. When the meter start detection flag is confirmed to be in the reset state, the current meter detection cycle ends.

[0159] Step S127: Check that the electricity meter is communicating normally and that the photovoltaic system is connected to the grid.

[0160] If the current state cannot simultaneously meet the conditions of normal meter communication and grid-connected operation of the photovoltaic system, the current meter detection cycle will end.

[0161] If the current state simultaneously meets the conditions of normal meter communication and grid-connected operation of the photovoltaic system, proceed to step S128.

[0162] Step S128: Set the meter wiring detection flag to zero, and clear the detection count, number of non-misconnection detections, and number of misconnection detections.

[0163] Step S129: Obtain the reactive power detected by each detection branch of the current meter.

[0164] Step S130: Confirm whether the power meter reading is stable.

[0165] It is understood that the specific execution process of step S130 can be referred to in steps S111 and S112 above, which describe the process of determining whether the power is stable based on the power fluctuation data, and will not be repeated here.

[0166] Step S131: Confirm whether the number of tests k is less than 4.

[0167] In some embodiments, the preset number of detections is 4. In other embodiments, the preset number of detections may be other values, and this application does not limit this.

[0168] When the number of tests k is less than 4, the process jumps to step S132. When the number of tests k is greater than 4, the current meter testing cycle ends.

[0169] Step S132: Record the reactive power detected by each detection branch of the meter in the previous test as the first detected reactive power.

[0170] Step S133: Inject reactive power into each phase line of the multiphase inverter according to the change in input reactive power corresponding to each phase line.

[0171] Step S134: Record the reactive power detected by each detection branch of the meter as the second detected reactive power.

[0172] Step S135: Confirm whether the power meter reading is stable.

[0173] It is understood that the specific execution process of step S135 can be referred to in steps S111 and S112 above, which describe the process of determining whether the power is stable based on the power fluctuation data, and will not be repeated here.

[0174] Step S136: When it is confirmed that the power of the meter is unstable, the meter detection is confirmed to have failed, and the process jumps to step S146.

[0175] Step S137: Calculate the change in reactive power detected by each detection branch based on the first and second detected reactive power detected by each detection branch; calculate the deviation between the absolute value of the change in reactive power detected and the absolute value of the change in the corresponding input reactive power based on the preset correspondence; increment the number of detections k by 1.

[0176] For the specific execution process, please refer to the relevant descriptions in steps S901-S902 above, which will not be repeated here.

[0177] Step S138: Confirm that the absolute value of all deviation values ​​is less than or equal to the preset error threshold.

[0178] If the judgment result in step S138 is yes, proceed to step S139; if the result is no, proceed to step S144.

[0179] Step S139: Perform reverse connection detection and phase sequence detection; increment the number of non-misconnection detections m by 1.

[0180] It is understandable that if the absolute value of all deviation values ​​is less than or equal to the preset error threshold, it indicates that there is no wiring error in meter 30, and reverse connection detection and phase sequence detection can continue.

[0181] The execution process of reverse connection detection and phase sequence detection can be found above and will not be repeated here.

[0182] Step S140: Confirm whether the number of non-misconnection detections m is greater than 2 or m equal to 2.

[0183] Specifically, if the number of non-misconnection detections m is confirmed to be less than 2, return to step S131. If the number of non-misconnection detections m is confirmed to be greater than or equal to 2, jump to step S141.

[0184] Step S141: Confirm whether the reverse connection test results are the same for two consecutive times, and whether the phase sequence test results are the same for two consecutive times.

[0185] If the result of step S141 is yes, proceed to step S142; if the result of step S142 is no, return to step S131.

[0186] Step S142: Save the test results; clear k, m and n; set the meter test end flag.

[0187] Step S143: Set the meter detection completion flag.

[0188] Step S144: End the current meter detection cycle.

[0189] Step S145: If the absolute value of all deviation values ​​cannot be less than or equal to the preset error threshold, increment the number of incorrect connections of the electricity meter by 1.

[0190] Step S146: Determine if the number of incorrect meter connections n is equal to 4.

[0191] Specifically, when it is determined that the number of incorrect connections n of the electricity meter is equal to 4, the process jumps to step S147; when it is determined that the number of incorrect connections n of the electricity meter is less than 4, the process returns to step S131.

[0192] Step S147: Save the test results; clear k, m and n; set the meter test end flag; report the meter misconnection fault alarm.

[0193] Step S148: Set the meter detection completion flag; re-detect upon next power-on.

[0194] In summary, by executing steps S121 to S148, it is possible to determine whether the meter 30 has a wiring error, reverse connection error, or phase sequence error, accurately locate the error type of the meter 30, and realize the periodic execution of the meter detection method.

[0195] In particular, when a reverse connection error and / or phase sequence error occurs in the meter, the meter 30 directly updates the preset correspondence between each phase line and the detection branch based on the meter's detection results. Thus, without reconnecting the meter 30, the updated preset correspondence can be used to obtain accurate detection data for calculation, thereby simplifying user operation.

[0196] In some embodiments, the multiphase inverter 103 also injects reactive power into each phase line according to the following formula.

[0197]

[0198] Where k is the number of detections, and when k = 0 or 2, Q set_r Q represents the first input reactive power of phase A1; set_s Q represents the first input reactive power of phase B1; set_t This represents the first input reactive power of phase C1. When k = 1 or 3, Q... set_r Q represents the second input reactive power of phase A1; set_s Q is the second input reactive power of phase B1; set_t Q is the second input reactive power of phase C1, where Q A Q B 、and Q C They are not equal. Furthermore, reverse connection detection and phase sequence detection are performed when k=1 or k=3.

[0199] Thus, combining the above formulas and Figure 12 The flowchart shown simplifies the adjustment process of the first and second input reactive power, reducing computational effort.

[0200] Please refer to the following: Figure 1 and Figure 13One embodiment of this application also provides a power conversion device 200, which includes a multiphase inverter 103 and a controller 201. At least two phase lines of the AC terminal of the multiphase inverter 103 are connected to the power grid 40 through a meter 30. The meter 30 includes at least two detection branches 301, which are used to detect the real-time reactive power transmitted on the corresponding phase lines. The controller 201 is used to execute the meter detection method as described in any of the above embodiments.

[0201] Please refer to the following: Figure 2 and Figure 14 This application also provides an energy storage device 300 in one embodiment. The energy storage device 300 includes a multiphase inverter 103, a controller 301, and an energy storage battery 302. At least two phases of the AC terminal of the multiphase inverter 103 are connected to the power grid 40 via a meter 30. The meter 30 includes at least two detection branches 301, which are used to detect the real-time reactive power transmitted on the corresponding phases. The controller 301 is used to execute the meter detection method as described in any of the above embodiments.

[0202] In some embodiments, the controller 301 is also electrically connected to the energy storage battery 302, and the energy storage battery 302 is connected to the DC terminal of the multiphase inverter 103 via a DC bus. Thus, the controller 301 can also use the energy storage battery 302 to store electrical energy, or convert the DC power released by the energy storage battery 302 into AC power through the multiphase inverter 103 to power the electrical load 20.

[0203] In some embodiments, the MPPT circuit 102 may also be integrated into the energy storage device 300, and the energy storage device 300 is provided with a photovoltaic interface for connecting the photovoltaic module 101.

[0204] Understandably, the controllers 201 and 301 mentioned in this application may be microcontroller units, central processing units, or digital signal processors, etc. The memory may be a Flash chip, read-only memory, disk, optical disk, USB flash drive, or portable hard drive, etc.

[0205] Please see Figure 15 This application also provides a computer-readable storage medium 400, including a computer program 401. When executed by controller 201 or controller 301, the computer program 401 implements the meter detection method described in the above technical solutions. The computer-readable storage medium may be a portable compact disk read-only memory (CD-ROM) and include program code, and may run on an electronic device, such as a power conversion device 200 or an energy storage device 300. However, the program product of this invention is not limited thereto. In this document, the readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0206] The above-described program product may employ any combination of one or more readable media. A readable medium may be a readable signal medium or a readable storage medium. A readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of readable storage media (a non-exhaustive list) include: electrical connections having one or more wires, portable disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0207] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A readable signal medium may also be any readable medium other than a readable storage medium, capable of sending, propagating, or transmitting programs for use by or in conjunction with an instruction execution system, apparatus, or device.

[0208] The program code contained on the readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination thereof.

[0209] Program code for performing the operations of this invention can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java and C++, and conventional procedural programming languages ​​such as C or similar languages. The program code can execute entirely on the user's computing device, partially on the user's device, as a standalone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In cases involving remote computing devices, the remote computing device can be connected to the user's computing device via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computing device (e.g., via the Internet using an Internet service provider).

[0210] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0211] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for testing electricity meters, applied to multiphase inverters, characterized in that, At least two phase lines of the AC terminal of the multiphase inverter are connected to the power grid via a meter, the meter including at least two detection branches, the detection branches being used to detect the real-time reactive power transmitted on the corresponding phase lines, the method including: The corresponding first input reactive power is injected into each of the phase lines respectively; The first detected reactive power detected by each of the detection branches is obtained respectively; Based on the change in input reactive power corresponding to each phase line, the first input reactive power injected into each phase line is adjusted to the corresponding second input reactive power; wherein, the change in input reactive power corresponding to each phase line is not equal. The second detected reactive power detected by each of the detection branches is obtained respectively; Based on the first detected reactive power and the second detected reactive power detected by each of the detection branches, calculate the change in detected reactive power corresponding to each detection branch; The wiring test result of the meter is determined based on the change in input reactive power corresponding to each phase line and the change in detected reactive power corresponding to each detection branch.

2. The meter testing method according to claim 1, characterized in that, The step of determining the wiring test result of the electricity meter based on the input reactive power change corresponding to each phase line and the detected reactive power change corresponding to each detection branch includes: Based on the change in input reactive power corresponding to each phase line, the change range corresponding to each phase line is determined, wherein each change range does not overlap. The reactive power change corresponding to each detection branch is matched with each change range to determine the phase line that is actually detected by each detection branch.

3. The meter testing method according to claim 2, characterized in that, The step of determining the wiring test result of the meter based on the input reactive power change corresponding to each phase line and the detected reactive power change corresponding to each detection branch further includes: When any of the detected reactive power changes does not match any of the change ranges, a wiring error is determined.

4. The meter testing method according to claim 1, characterized in that, The multiphase inverter is configured with a preset correspondence between the phase lines and the detection branches; The step of determining the wiring test result of the electricity meter based on the input reactive power change corresponding to each phase line and the detected reactive power change corresponding to each detection branch includes: According to the preset correspondence, the deviation between the absolute value of each detected reactive power change and the absolute value of the corresponding input reactive power change is calculated; When the absolute value of all the deviation values ​​is less than or equal to the preset error threshold, the preset correspondence is determined to be correct.

5. The meter testing method according to claim 4, characterized in that, The step of determining the wiring test result of the meter based on the input reactive power change corresponding to each phase line and the detected reactive power change corresponding to each detection branch further includes: When the absolute value of any of the aforementioned deviation values ​​is greater than a preset error threshold, it is determined that there is a wiring error or a phase sequence error.

6. The meter testing method according to claim 1, characterized in that, The step of determining the wiring test result of the electricity meter based on the input reactive power change corresponding to each phase line and the detected reactive power change corresponding to each detection branch includes: The absolute values ​​of each input reactive power change are sorted according to the same sorting method, and the absolute values ​​of each detected reactive power change are also sorted. Calculate the deviation between the absolute value of the input reactive power change and the absolute value of the detected reactive power change for the same ranking; When the absolute value of any of the aforementioned deviation values ​​is greater than a preset error threshold, a wiring error is determined to exist.

7. The meter testing method according to claim 1, characterized in that, The step of determining the wiring test result of the electricity meter based on the input reactive power change corresponding to each phase line and the detected reactive power change corresponding to each detection branch includes: The reverse connection detection result of the corresponding detection branch is determined based on the sign of the detected reactive power change.

8. The meter testing method according to claim 7, characterized in that, The step of determining the reverse connection detection result of the corresponding detection branch based on the sign of the detected reactive power change includes: When the sign of the detected reactive power change is inconsistent with the preset sign, and the absolute value of the detected reactive power change is greater than the preset measurement deviation threshold, it is determined that there is a reverse connection error in the detection branch corresponding to the detected reactive power change.

9. The meter testing method according to claim 1, characterized in that, Before injecting the corresponding first input reactive power into each of the phase lines, the method further includes: The power fluctuation data of the reactive power sampled by the meter within a preset time period is detected; When the power fluctuation data are all less than the preset fluctuation threshold, the step of injecting the corresponding first input reactive power into each phase line is executed.

10. A power conversion device, characterized in that, The device includes a multiphase inverter and a controller. At least two phase lines of the AC terminal of the multiphase inverter are connected to the power grid via a meter. The meter includes at least two detection branches, which are used to detect the real-time reactive power transmitted on the corresponding phase lines. The controller is used to execute the meter detection method as described in any one of claims 1 to 9.

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